Why can cows digest cellulose?
To digest cellulose you need to produce cellulases (to break down the D glucose linkages). Most animals don’t have cellulases. Even termites and they eat wood all day. They all need symbionts to break down the cellulose which they store in their rumen or caecum, etc. The microbes in ruminants and humans, etc can produce cellulase, as can some other bacteria and fungi. I don’t know what ship worms are but if they can digest cellulose without symbionts, then they must produce their own cellulase.
